Oil firing system



P. J. OLDE- OIL FIRENG SYSTEM Filed Dec.

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United States Patent 3,323,573 01L FIRENG SYSTEM Peter John ()ld's, Maryborough, Queensland, Australia, assignor of one-half to Cooroy Brickworlrs Pty. Ltd, Conroy, Queensland, and one-fourth to William Ulds, Maryborough, Queensland, Australia Filed Dec. 23, 1964, Ser. No. 420,585 14 Claims. (Cl. 158-36) This invention relates to 'an improved oil firing system.

In a kiln, for example, it is known to use burners to which heavy fuel oil and air are fed under pressure, so that the air atomizes the oil to ensure efiicient combustion.

Such oil burners require frequent maintenance owing to rapid build up of deposits at the burner tips, due to oxidation of oil.

The present invention has the main object of overcoming this disadvantage, by providing an oil firing systern wherein the oxidation of oil at the burner tips will be very materially reduced.

The invention resides broadly in an oil firing system of the type including a burner, an outlet orifice from the burner, means for feeding fuel oil under pressure to the burner, and means for feeding gas under pressure to the burner to atomize the fuel oil ejected from the outlet orifice of the burner; characterized in that the gas fed to the burner to atomize the fuel oil is a reducing gas. Preferably the reducing gas is exhaust gas from an internal combustion engine, which also serves to drive a pump for feeding the oil under pressure, waste heat from the engine being utilized to preheat the fuel oil.

In the drawings:

FIG. 1 is a diagrammatic drawing illustrating the general arrangement of an oil firing system according to the invention,

FIG. 2 is a sectional view of the diaphragm balance valve of the arrangement,

FIG. 3 is a partly broken-away view of a header as sembly used in an oil firing system according to the in vention,

FIG. 4 is a diagrammatic drawing showing the general arrangement of an oil firing system in an alternative embodiment of the invention, and

FIG. 5 is a sectional view of the float balance valve of the arrangement shown in FIG. 4.

The oil firing system shown in FIGS. 1, 2 and 3 may be used, for example, in a brick kiln, and includes a storage tank 1t), for heavy fuel oil. Oil is drawn from this tank through an oil line 11 and a filter 12 by a pump 13, driven at 14 by a belt drive from an internal combustion engine 15. This engine is of normally water-cooled type, and has any suitable governor to maintain its speed substantially constant. As the engine 15 is required to exhaust against a gas head pressure, the profile of its cam shaft is modified so the different operation of the valves enables the engine to be run whilst delivering its exhaust gas into the system under pressure.

From the pump 13, the oil is fed under pressure through an oil line 16 into the jacket 17 of the engine, and after flowing through the jacket, cooling the engine and being heated thereby, it enters a heat exchanger 18 into which the hot engine exhaust gas is also fed, and by heat transfer the oil is heated, the exhaust gas is cooled.

From the heat exchanger 18, the heated oil passes through an oil line 19, and the exhaust gas passes through a gas line 20. Connected to the oil line 19 are a thermometer 21 and a pressure gauge 22. Connected to the gas line is a branch line to an adjustable pressure relief valve 23.

The oil and gas lines 19 and 20 lead into a diaphragm balance valve 24 (see FIG. 2) with a body having similar upper and lower parts 25 and 26 oppositely arranged, each hollowed and with a central drilled and tapped boss 27, and peripheral flanges secured and sealed to the interposed periphery of a thin metal diaphragm 28 having washers 29 above and below its middle. Above the diaphragm is a valve 30 with a tapered upper end and a reduced and threaded lower end passed through the Washers 29 and diaphragm 27 and engaged by a nut 31.

A tubular valve seating member 32 is screwed into the upper boss 2'7, the lower end of the bore of this member constituting a seating 33 for the valve 30. When the diaphragm 28 is undistorted, as shown, there is a clearance between the valve 30 and its seating 33".

A threaded axially bored bush 34 is screwed into the lower boss 27, and a cap 35 is screwed onto its lower end. Slidably engaged in the bush 34 is a spring seating 36 recessed to receive the lower end of a compression spring 37, the upper end of which bears the nut 31 about the lower end of the valve 34). A spring adjusting screw 38, engaged in the cap 35, bears on the underside of the spring seating 36, and by rotation of the screw, the springloading on the diaphragm 33 may be varied, for a purpose hereinafter explained.

The oil line 19 from the heat exchanger 18 leads into the upper part 25 of the balance valve body, and an oil line 39 leads from this part of the valve body.

The gas line 20 from the heat exchanger 18 leads into the lower part 26 of the balance valve body, and a gas line 40 leads from this lower part of the valve body.

An oil by-pass line 41 is connected to the balance valve seating member 32, and leads into the storage tank 10.

The gas line 40 is connected to the gas inlets 42 of a series of burners 43, and the oil line 39 is connected to their oil inlets 44. Each of the burners 43 is generally of the well-known type used for ejecting fairly heavy fuel oil under pressure and atomized by compressed air; but in the present invention the fuel oil under pressure is atomized by exhaust gas from the engine 15. The rate of flow of the oil and of the gas may be regulated by oil and gas control valves 45 and 46 respectively; and the tip of each burner, having a restricted orifice from which the atomized oil and gas are ejected, is indicated at 4'7.

From the extremity of the oil line 39, a return line 48 leads, through a circulation valve 49, to the oil line 11 from the tank 10 to the oil pump 13. v

Before commencing firing, the fuel oil may be heated to reduce its viscosity. With the circulation valve 49 open, the burner oil and gas control valves 45 and 46 closed, the engine 15 is operated to drive the pump 13, which delivers a greater flow of oil than is required for the burners 43, and consequently it draws oil from the tank 10 and from the oil line 39 supplying the burners. The oil, heated by its passage through the jacket 17 and the heat exchanger 15, enters the balance valve 24 above the diaphragm 28. The exhaust gas, at this stage, escapes to atmosphere through the pressure relief valve 23. A proportion of the heated oil is circulated through the oil line 39, and excess oil escapes past the partly open valve 39 and through the bypass line, for circulation through the tank 10. Thus the temperature of the oil in the burner system and also in the storage tank is raised.

On the commencement of firing, the burner oil and gas control valves 45 and 46 are opened and the circulation valve 4-9 is closed, so that the heated oil and the exhaust gas are fed through the burners. With the heating of the oil in the engine jacket 17, and the heat transfer between the exhaust gas and the oil in the heat exchanger 18, and also through the thin metal diaphragm 28 of the balance valve 24, the temperatures of the two will be more or less equalized. The burners 43 are operated in usual manner.

The balance valve 24 substantially equalizes the pressures of the gas and of the oil, may increase in the pressure of the gas causing the diaphragm 28 to move the valve 30 towards closed position, reducing the flow of oil returned through the by-pass line 41 to the tank, so that the oil pressure within the valve body is correspondingly raised. When the burners 43 are a considerable distance from the balance valve, it may be desired to maintain oil pressure in the balance valve at a somewhat higher level than the gas pressure, so that the pressures of the two will be balanced at the burners. An appropriate adjustment may be made by means of the spring adjusting screw 38, to cause the diaphragm to be suitably spring-loaded to achieve the desired result.

In an oil firing system where a considerable number of burners are required, it is preferred to use two or more engines; and even where only one engine is required to pro-heat the oil and provide the atomising gas for the burners used, it is desirable to provide a second engine which may be brought into operation in the event of failure, or to permit maintenance, of the other. The two or more engines are connected in the system in parallel by the use of a header assembly illustrated in FIG. 3, and including an elongated tubular oil header 50, within which there is mounted a co-axial tubular gas header 51 so there is a space between the two. These two header tubes and 51 are closed at both ends.

From each engine, an oil line 52 leads from its heat exchanger to the oil header 5t and from the oil header the single oil line 19, as before described, leads to the balance valve 24.

Exhaust gas from each engine is carried from its heat exchanger through a gas line 53 into the gas header 51 by way of a two-way valve fitting 54, having an inlet 55,

to which the line 53 is connected. The fitting also has a main gas outlet 56 screwed into a tube 57 leading through the oil header 50 into the gas header 51, and a blow-off gas outlet 58 to which a blow-off pipe 59 is connected, leading to atmosphere. By rotating a valve hand wheel 60, a two-way valve (not shown) may be raised within the fitting to connect the inlet to the main outlet 56, or lowered to connect the inlet 55 to the blow-off outlet 58. A single gas line 20, as before described, leads from one end of the gas header 51 to the diaphragm balance valve 24.

To cut one of the engines out of the circuit, its exhaust is first led to atmosphere by means of the appropriate two-way valve fitting 54, and in starting an engine to be brought into the circuit, its exhaust is initially carried to atmosphere, and subsequently, by means of the two-way valve fitting, is conducted into the gas header 51.

In this multiple-engine system each engine operates a pump, as before described, to draw oil from the common storage tank, and the single balance valve 24 is used; though to obviate the necessity of ceasing firing in the event of failure of the balance valve, two balance valves may be connected in parallel, with appropriate valves for bringing either one, as required, into the circuit and bypassing the other.

In the modification of the invention shown in FIGS. 4 and 5, a storage tank 61 contains fuel oil which is drawn through an oil line 62 with a filter 63 by a pump 64 operated by an engine 65, to the jacket 66 of which the oil is fed through an oil line 67, all these parts being substantially similar to the corresponding parts previously described with reference to FIG. 1. In this case, however, the heat exchanger used is a mixing device 68 of the type commonly provided on marine engines for the purpose of mixing exhaust gas from the engine with water which has been pumped through the engine jacket 65. According to the present invention, then, it is the fuel oil which, after being pumped through the engine jacket, is mixed with the exhaust gas from the engine, the mixture of oil and ex haust gas being fed under pressure through a conduit 6% to a float balance valve 70.

The float balance valve 70 (see FIG. 5) has a cylindrical body 71, closed at the bottom, and with a closure 72 secured and sealed to its top. Within the upper part of the body 71 is an annular bafiie 73, and slidable vertically in this baflle is a float 74, which is a hollow cylinder closed at the bottom and with a flange 75 about its open top. A stem 76, secured axially within the float 75, has its upper end slidable in an axial recess formed from the bottom of a boss 77 under the closure 72. A valve 78, extending co-axially downwards from the float bottom, engages in an axially bored valve seating member 79 screwed through a central tapped aperture in the bottom of the balance valve body 71. The valve 78 is tapered at its lower end, and a valve seating 80 is formed in the bore of the valve seating member 79. Radial oil passages 81 lead into the bore of the valve seating member 79 above the seating 88, and to the bottom end of thevalve seating member there is connected a by-pass oil line 82, leading back into the oil storage tank 61.

The conduit 69 for mixed exhaust gas and oil from the engine 65 leads tangentially into the float balance valve body at 83, immediately below the annular baffle 73. An oil line 84 leads from the lower part of the balance valve body 71, and a gas line 85 leads upwardly from within the float 74, and radially out from the upper part of the balance valve body 71.

To the oil line 84 and the gas line 85 a series of burners (not shown) are connected as before described with ref erence to FIG. 1; and from the extremity of the oil line 84 to the burners, a circulation line 86 leads back to the oil line 62 by way of a circulation valve 87 for the purpose before described.

In this form of the invention, the intimate mixture of oil, pre-heated in the engine jacket 66, with exhaust gas from the engine 65 results in an efi'icient heat exchange so that the oil and gas are at substantially the same temperature on entering the float balance valve 70. In the body 71 of this valve, the gas separates from the oil, the oil filling the lower part of the body, as indicated at 86A. the gas passing between the float 74 and the annular bafllc 73, past the peripheral flange 75, into the float and up through the gas line 85. The valve 78, controlled by the float 74-, maintains the level of oil substantially constant and, of course, the pressure of oil and gas are balanced within the balance valve body.

In another modification of the invention, the engine or engines used in the system are water cooled, the water being circulated through a heat exchanger by a suitable pump or pumps, driven by the engine or engines, and oil drawn from the storage tank being pro-heated by being passed through the heat exchanger.

Oil firing systems according to the invention will be found to be very effective in achieving the objects for which the invention has been devised. The gas employed for the atomization of the fuel oil is virtually oxygen free, and consequently it will be found that there will be no material fouling of the burners due to oxidization of the fuel oil. Only a small proportion of the oil heated by the engines is burnt during its cycle and therefore the oil in the storage tank is kept heated and free-flowing.

Very eflicient use is made of the engines used for pumping the oil, by utilizing their waste heat for pre-heating the oil, and their exhaust gas for atomizing the oil. Moreover, any one of the engines used in the system is also available for the provision of power for driving a fan, or boiler feed pump, for example. The system, being completely independent of outside power supply, will be free from interruptions during operation. Any one engine can be completely isolated, if required, for maintenance, without affecting the operation of the firing system.

What we claim is:

1. An oil firing system including a tank for fuel oil, an internal combustion engine, at least one burner of the type ejecting fuel oil delivered thereto under pressure and atomizing said oil by gas delivered thereto under pressure, delivery means for delivering fuel oil under pressure from said tank to said burner, and a conduit to convey exhaust gas from said engine to the burner under pressure to atomize the fuel oil delivered thereto.

2. An oil firing system as claimed in claim 1 wherein said delivery means include a pump to draw fuel oil from the tank and deliver it to the burner, and means for driving said pump from said engine.

3. An oil firing system as claimed in claim 2 including pre-heating means for pre-heating the fuel oil before delivering it to said burner.

4. An oil firing system as claimed in claim 3 wherein said pre-heating means include a heat exchanger, means for directing the fuel oil through said heat exchanger, and heat transfer means to transfer heat from said engine to the fuel oil through said heat exchanger.

5. An oil firing system as claimed in claim 4 wherein said heat exchanger consists of a cooling jacket on said engine.

6. An oil firing system as claimed in claim 4 wherein said heat exchanger includes means for effecting heat transfer between exhaust gas from the engine and said fuel oil.

7. An oil firing system including a tank for fuel oil, an internal combustion engine, at least one burner, delivery means for delivering fuel oil from said tank to said burner under pressure, a conduit to convey exhaust gas from said engine to said burner under pressure to atomize the fuel oil delivered thereto, and pressure-balancing means to maintain a predetermined relationship between the pressures of the fuel oil and the exhaust gas delivered to said burner.

8. An oil firing system as claimed in claim 7 wherein said pressure-balancing means include a diaphragm balanoe valve, said delivery means delivering fuel oil from said tank to said burner by way of said balance valve at an excessive rate of flow, a by-pass line from said balance valve to said tank to return excess oil from the balance valve to the tank, said conduit conveying exhaust gas to said burner by Way of the balance valve, the balance valve, on an increase in pressure of the gas, restricting said by-pass line to increase correspondingly the pressure of the fuel oil.

9. An oil firing system as claimed in claim 8 including adjustable spring-loading means on said diaphragm bal ance valve to cause a pressure differential between said fuel oil and said exhaust gas.

10. An oil firing system including a tank for fuel oil, a float balance valve, a pump for delivering oil from said tank through a first conduit to said valve at an excessive rate of flow, an internal combustion engine, a second conduit conveying exhaust gas from said engine to said first conduit between said tank and said valve, a bypass line to return excess oil from said valve to said tank and means in said valve to restrict said by-pass line on decrease of level of oil in said valve, a burner, and separate connections from said valve to supply exhaust gas and oil under pressure to said burner.

11. An oil firing system as claimed in. claim 10, including drive means between said engine and said pump.

12. An oil firing system including a tank for fuel oil, a burner, a pump for delivering fuel oil under pressure from said tank to an oil header to said burner, a plurality of internal combustion engines, a gas header in heat exchange relationship with said oil header, a connection from the exhaust of each said engine to said gas header, a conduit from said gas header to supply exhaust gas under pressure to said burner, and a conduit from said oil header to said burner to supply fuel oil under pressure to said burner.

13. An oil firing system as claimed in claim 12, in which each said connection includes a two-way valve to direct exhaust gas either to said gas header or to atmosphere.

14. A method of oil firing including the steps of preheating fuel oil by heat transfer from an internal combustion engine, feeding the pre-heated oil under pressure to a burner, and simultaneously feeding exhaust gas from said internal combustion engine to the burner under pressure to atomize the fuel oil.

2,907,527 10/ 1959 Cummings.

FREDERICK L. MATTESON, JR., Primary Examiner. ROBERT A. DUA, Examiner. 

1. AN OIL FIRING SYSTEM INCLUDING A TANK FOR FUEL OIL, AN INTERNAL COMBUSTION ENGINE, AT LEAST ONE BURNER OF THE TYPE EJECTING FUEL OIL DELIVERED THERETO UNDER PRESSURE AND ATOMIZING SAID OIL BY GAS DELIVERED THERETO UNDER PRESSURE, DELIVERY MEANS FOR DELIVERING FUEL OIL UNDER PRESSURE FROM SAID TANK TO SAID BURNER, AND A CONDUIT TO CONVEY EXHAUST GAS FROM SAID ENGINE TO THE BURNER UNDER PRESSURE TO ATOMIZE THE FUEL OIL DELIVERED THERETO. 